351
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Magraoui FE, Reidick C, Meyer HE, Platta HW. Autophagy-Related Deubiquitinating Enzymes Involved in Health and Disease. Cells 2015; 4:596-621. [PMID: 26445063 PMCID: PMC4695848 DOI: 10.3390/cells4040596] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/15/2015] [Accepted: 09/30/2015] [Indexed: 02/06/2023] Open
Abstract
Autophagy is an evolutionarily-conserved process that delivers diverse cytoplasmic components to the lysosomal compartment for either recycling or degradation. This involves the removal of protein aggregates, the turnover of organelles, as well as the elimination of intracellular pathogens. In this situation, when only specific cargoes should be targeted to the lysosome, the potential targets can be selectively marked by the attachment of ubiquitin in order to be recognized by autophagy-receptors. Ubiquitination plays a central role in this process, because it regulates early signaling events during the induction of autophagy and is also used as a degradation-tag on the potential autophagic cargo protein. Here, we review how the ubiquitin-dependent steps of autophagy are balanced or counteracted by deubiquitination events. Moreover, we highlight the functional role of the corresponding deubiquitinating enzymes and discuss how they might be involved in the occurrence of cancer, neurodegenerative diseases or infection with pathogenic bacteria.
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Affiliation(s)
- Fouzi El Magraoui
- Biomedizinische Forschung, Human Brain Proteomics II, Leibniz-Institut für Analytische Wissenschaften - ISAS -e.V. 44139 Dortmund, Germany.
| | - Christina Reidick
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Hemut E Meyer
- Biomedizinische Forschung, Human Brain Proteomics II, Leibniz-Institut für Analytische Wissenschaften - ISAS -e.V. 44139 Dortmund, Germany.
| | - Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44801 Bochum, Germany.
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352
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Sbiera S, Deutschbein T, Weigand I, Reincke M, Fassnacht M, Allolio B. The New Molecular Landscape of Cushing's Disease. Trends Endocrinol Metab 2015; 26:573-583. [PMID: 26412158 DOI: 10.1016/j.tem.2015.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/05/2015] [Accepted: 08/08/2015] [Indexed: 11/21/2022]
Abstract
Cushing's disease (CD) is caused by corticotropin-secreting pituitary adenomas and results in substantial morbidity and mortality. Its molecular basis has remained poorly understood until the past few years, when several proteins and genes [such as testicular orphan nuclear receptor 4 (TR4) and heat shock protein 90 (HSP90)] were found to play key roles in the disease. Most recently, mutations in the gene of ubiquitin-specific peptidase 8 (USP8) increasing its deubiquination activity were discovered in a high percentage of corticotroph adenomas. Here, we will discuss emerging insights in the molecular alterations that finally result in CD. The therapeutic potential of these findings needs to be carefully evaluated in the near future, hopefully resulting in new treatment options for this devastating disorder.
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Affiliation(s)
- Silviu Sbiera
- Department of Internal Medicine I, Endocrine and Diabetes Unit, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Timo Deutschbein
- Department of Internal Medicine I, Endocrine and Diabetes Unit, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Isabel Weigand
- Department of Internal Medicine I, Endocrine and Diabetes Unit, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Martin Reincke
- Endocrine Research Unit, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany
| | - Martin Fassnacht
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
| | - Bruno Allolio
- Department of Internal Medicine I, Endocrine and Diabetes Unit, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
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353
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Theodoropoulou M, Reincke M, Fassnacht M, Komada M. Decoding the genetic basis of Cushing's disease: USP8 in the spotlight. Eur J Endocrinol 2015; 173:M73-83. [PMID: 26012588 DOI: 10.1530/eje-15-0320] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 05/26/2015] [Indexed: 12/28/2022]
Abstract
Cushing's disease (CD) arises from pituitary-dependent glucocorticoid excess due to an ACTH-secreting corticotroph tumor. Genetic hits in oncogenes and tumor suppressor genes that afflict other pituitary tumor subtypes are not found in corticotrophinomas. Recently, a somatic mutational hotspot was found in up to half of corticotrophinomas in the USP8 gene that encodes a protein that impairs the downregulation of the epidermal growth factor receptor (EGFR) and enables its constitutive signaling. EGF is an important regulator of corticotroph function and its receptor is highly expressed in Cushing's pituitary tumors, where it leads to increased ACTH synthesis in vitro and in vivo. The mutational hotspot found in corticotrophinomas hyper-activates USP8, enabling it to rescue EGFR from lysosomal degradation and ensure its stimulatory signaling. This review presents new developments in the study of the genetics of CD and focuses on the USP8-EGFR system as trigger and target of corticotroph tumorigenesis.
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Affiliation(s)
- Marily Theodoropoulou
- Department of EndocrinologyMax Planck Institute of Psychiatry, Kraepelinstrasse 10, Munich 80804, GermanyMedizinische Klinik und Poliklinik IVLudwig-Maximilians-Universität München, Munich, GermanyEndocrine and Diabetes UnitDepartment of Medicine I, University Hospital, University of Würzburg, Würzburg, GermanyDepartment of Biological SciencesTokyo Institute of Technology, 4259-B16 Nagatsuta, Midori, Yokohama 226-8501, Japan
| | - Martin Reincke
- Department of EndocrinologyMax Planck Institute of Psychiatry, Kraepelinstrasse 10, Munich 80804, GermanyMedizinische Klinik und Poliklinik IVLudwig-Maximilians-Universität München, Munich, GermanyEndocrine and Diabetes UnitDepartment of Medicine I, University Hospital, University of Würzburg, Würzburg, GermanyDepartment of Biological SciencesTokyo Institute of Technology, 4259-B16 Nagatsuta, Midori, Yokohama 226-8501, Japan
| | - Martin Fassnacht
- Department of EndocrinologyMax Planck Institute of Psychiatry, Kraepelinstrasse 10, Munich 80804, GermanyMedizinische Klinik und Poliklinik IVLudwig-Maximilians-Universität München, Munich, GermanyEndocrine and Diabetes UnitDepartment of Medicine I, University Hospital, University of Würzburg, Würzburg, GermanyDepartment of Biological SciencesTokyo Institute of Technology, 4259-B16 Nagatsuta, Midori, Yokohama 226-8501, Japan
| | - Masayuki Komada
- Department of EndocrinologyMax Planck Institute of Psychiatry, Kraepelinstrasse 10, Munich 80804, GermanyMedizinische Klinik und Poliklinik IVLudwig-Maximilians-Universität München, Munich, GermanyEndocrine and Diabetes UnitDepartment of Medicine I, University Hospital, University of Würzburg, Würzburg, GermanyDepartment of Biological SciencesTokyo Institute of Technology, 4259-B16 Nagatsuta, Midori, Yokohama 226-8501, Japan
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354
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El Ghorayeb N, Bourdeau I, Lacroix A. Multiple aberrant hormone receptors in Cushing's syndrome. Eur J Endocrinol 2015; 173:M45-60. [PMID: 25971648 DOI: 10.1530/eje-15-0200] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/12/2015] [Indexed: 01/19/2023]
Abstract
The mechanisms regulating cortisol production when ACTH of pituitary origin is suppressed in primary adrenal causes of Cushing's syndrome (CS) include diverse genetic and molecular mechanisms. These can lead either to constitutive activation of the cAMP system and steroidogenesis or to its regulation exerted by the aberrant adrenal expression of several hormone receptors, particularly G-protein coupled hormone receptors (GPCR) and their ligands. Screening for aberrant expression of GPCR in bilateral macronodular adrenal hyperplasia (BMAH) and unilateral adrenal tumors of patients with overt or subclinical CS demonstrates the frequent co-expression of several receptors. Aberrant hormone receptors can also exert their activity by regulating the paracrine secretion of ACTH or other ligands for those receptors in BMAH or unilateral tumors. The aberrant expression of hormone receptors is not limited to adrenal CS but can be implicated in other endocrine tumors including primary aldosteronism and Cushing's disease. Targeted therapies to block the aberrant receptors or their ligands could become useful in the future.
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MESH Headings
- Adenoma/metabolism
- Adrenal Gland Neoplasms/metabolism
- Cushing Syndrome/metabolism
- Cyclic AMP/metabolism
- Gene Expression
- Humans
- Receptor, Melanocortin, Type 2/metabolism
- Receptors, Adrenergic, beta/metabolism
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Gastrointestinal Hormone/metabolism
- Receptors, Glucagon/metabolism
- Receptors, LH/metabolism
- Receptors, Serotonin, 5-HT4/metabolism
- Receptors, Vasopressin/metabolism
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Affiliation(s)
- Nada El Ghorayeb
- Division of EndocrinologyDepartment of Medicine, Centre de recherche du CHUM (CRCHUM), Université de Montréal, 900, Rue Saint-Denis, Room R08-474, Montréal, Québec H2X 0A9, Canada
| | - Isabelle Bourdeau
- Division of EndocrinologyDepartment of Medicine, Centre de recherche du CHUM (CRCHUM), Université de Montréal, 900, Rue Saint-Denis, Room R08-474, Montréal, Québec H2X 0A9, Canada
| | - André Lacroix
- Division of EndocrinologyDepartment of Medicine, Centre de recherche du CHUM (CRCHUM), Université de Montréal, 900, Rue Saint-Denis, Room R08-474, Montréal, Québec H2X 0A9, Canada
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355
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Abstract
Chronic exposure to excess glucorticoids results in diverse manifestations of Cushing's syndrome, including debilitating morbidities and increased mortality. Genetic and molecular mechanisms responsible for excess cortisol secretion by primary adrenal lesions and adrenocorticotropic hormone (ACTH) secretion from corticotroph or ectopic tumours have been identified. New biochemical and imaging diagnostic approaches and progress in surgical and radiotherapy techniques have improved the management of patients. The therapeutic goal is to normalise tissue exposure to cortisol to reverse increased morbidity and mortality. Optimum treatment consisting of selective and complete resection of the causative tumour is necessay to allow eventual normalisation of the hypothalamic-pituitary-adrenal axis, maintenance of pituitary function, and avoidance of tumour recurrence. The development of new drugs offers clinicians several choices to treat patients with residual cortisol excess. However, for patients affected by this challenging syndrome, the long-term effects and comorbidities associated with hypercortisolism need ongoing care.
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Affiliation(s)
- André Lacroix
- Division of Endocrinology, Department of Medicine and Research Center, Centre hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada.
| | - Richard A Feelders
- Division of Endocrinology, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Constantine A Stratakis
- Section on Genetics and Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Lynnette K Nieman
- Program on Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
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356
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Dufner A, Kisser A, Niendorf S, Basters A, Reissig S, Schönle A, Aichem A, Kurz T, Schlosser A, Yablonski D, Groettrup M, Buch T, Waisman A, Schamel WW, Prinz M, Knobeloch KP. The ubiquitin-specific protease USP8 is critical for the development and homeostasis of T cells. Nat Immunol 2015. [PMID: 26214742 DOI: 10.1038/ni.3230] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The modification of proteins by ubiquitin has a major role in cells of the immune system and is counteracted by various deubiquitinating enzymes (DUBs) with poorly defined functions. Here we identified the ubiquitin-specific protease USP8 as a regulatory component of the T cell antigen receptor (TCR) signalosome that interacted with the adaptor Gads and the regulatory molecule 14-3-3β. Caspase-dependent processing of USP8 occurred after stimulation of the TCR. T cell-specific deletion of USP8 in mice revealed that USP8 was essential for thymocyte maturation and upregulation of the gene encoding the cytokine receptor IL-7Rα mediated by the transcription factor Foxo1. Mice with T cell-specific USP8 deficiency developed colitis that was promoted by disturbed T cell homeostasis, a predominance of CD8(+) γδ T cells in the intestine and impaired regulatory T cell function. Collectively, our data reveal an unexpected role for USP8 as an immunomodulatory DUB in T cells.
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Affiliation(s)
- Almut Dufner
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany
| | - Agnes Kisser
- Leibniz Institute for Molecular Pharmacology, Berlin, Germany
| | - Sandra Niendorf
- Leibniz Institute for Molecular Pharmacology, Berlin, Germany
| | - Anja Basters
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany
| | - Sonja Reissig
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Anne Schönle
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany
| | - Annette Aichem
- Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | - Thorsten Kurz
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Andreas Schlosser
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Deborah Yablonski
- Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Marcus Groettrup
- 1] Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland. [2] Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Thorsten Buch
- 1] Institute for Medical Microbiology, Immunology, and Hygiene, Technische Universität München, Germany. [2] Institute of Laboratory Animal Sciences, University of Zurich, Zurich, Switzerland
| | - Ari Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Wolfgang W Schamel
- 1] Department of Molecular Immunology, Faculty of Biology, and Center of Chronic Immunodeficiency, University of Freiburg, Freiburg, Germany. [2] BIOSS Center for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Marco Prinz
- 1] Institute of Neuropathology, University of Freiburg, Freiburg, Germany. [2] BIOSS Center for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Klaus-Peter Knobeloch
- 1] Institute of Neuropathology, University of Freiburg, Freiburg, Germany. [2] Leibniz Institute for Molecular Pharmacology, Berlin, Germany
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357
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Perez-Rivas LG, Theodoropoulou M, Ferraù F, Nusser C, Kawaguchi K, Stratakis CA, Faucz FR, Wildemberg LE, Assié G, Beschorner R, Dimopoulou C, Buchfelder M, Popovic V, Berr CM, Tóth M, Ardisasmita AI, Honegger J, Bertherat J, Gadelha MR, Beuschlein F, Stalla G, Komada M, Korbonits M, Reincke M. The Gene of the Ubiquitin-Specific Protease 8 Is Frequently Mutated in Adenomas Causing Cushing's Disease. J Clin Endocrinol Metab 2015; 100:E997-1004. [PMID: 25942478 PMCID: PMC4490309 DOI: 10.1210/jc.2015-1453] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
CONTEXT We have recently reported somatic mutations in the ubiquitin-specific protease USP8 gene in a small series of adenomas of patients with Cushing's disease. OBJECTIVE To determine the prevalence of USP8 mutations and the genotype-phenotype correlation in a large series of patients diagnosed with Cushing's disease. DESIGN We performed a retrospective, multicentric, genetic analysis of 134 functioning and 11 silent corticotroph adenomas using Sanger sequencing. Biochemical and clinical features were collected and examined within the context of the mutational status of USP8, and new mutations were characterized by functional studies. PATIENTS A total of 145 patients who underwent surgery for an ACTH-producing pituitary adenoma. MAIN OUTCOMES MEASURES Mutational status of USP8. Biochemical and clinical features included sex, age at diagnosis, tumor size, preoperative and postoperative hormonal levels, and comorbidities. RESULTS We found somatic mutations in USP8 in 48 (36%) pituitary adenomas from patients with Cushing's disease but in none of 11 silent corticotropinomas. The prevalence was higher in adults than in pediatric cases (41 vs 17%) and in females than in males (43 vs 17%). Adults having USP8-mutated adenomas were diagnosed at an earlier age than those with wild-type lesions (36 vs 44 y). Mutations were primarily found in adenomas of 10 ± 7 mm and were inversely associated with the development of postoperative adrenal insufficiency. All the mutations affected the residues Ser718 or Pro720, including five new identified alterations. Mutations reduced the interaction between USP8 and 14-3-3 and enhanced USP8 activity. USP8 mutants diminished epidermal growth factor receptor ubiquitination and induced Pomc promoter activity in immortalized AtT-20 corticotropinoma cells. CONCLUSIONS USP8 is frequently mutated in adenomas causing Cushing's disease, especially in those from female adult patients diagnosed at a younger age.
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358
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Abstract
Cushing's disease (CD) is the commonest form of ACTH-dependent Cushing's syndrome and is a rare clinical diagnosis in paediatric and adolescent patients. CD is caused by an ACTH-secreting pituitary corticotroph adenoma and is associated with significant morbidity in children; therefore, early diagnosis and treatment are critical for optimal therapeutic outcome. This review highlights the key clinical and biochemical features of paediatric CD and appraises current practices in diagnosis and management. A close liaison with adult endocrinology colleagues, particularly, for interpretation of investigations and definition of therapeutic strategy is strongly advised.
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Affiliation(s)
- Helen L Storr
- Barts and the London School of Medicine and DentistryWilliam Harvey Research Institute, Centre for Endocrinology, Queen Mary University of London, 1st Floor, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Martin O Savage
- Barts and the London School of Medicine and DentistryWilliam Harvey Research Institute, Centre for Endocrinology, Queen Mary University of London, 1st Floor, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
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359
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D'Angelo D, Esposito F, Fusco A. Epigenetic Mechanisms Leading to Overexpression of HMGA Proteins in Human Pituitary Adenomas. Front Med (Lausanne) 2015; 2:39. [PMID: 26137461 PMCID: PMC4469109 DOI: 10.3389/fmed.2015.00039] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/23/2015] [Indexed: 01/06/2023] Open
Abstract
Overexpression of the high-mobility group A (HMGA)1 and HMGA2 proteins is a feature of all human pituitary adenoma (PAs) subtypes. However, amplification and/or rearrangement of the HMGA2 have been described in human prolactinomas, but rarely in other pituitary subtypes, and no genomic amplification of HMGA1 was detected in PAs. Here, we summarize the functional role of HMGA proteins in pituitary tumorigenesis and the epigenetic mechanisms contributing to HMGA overexpression in these tumors focusing on recent studies indicating a critical role of non-coding RNAs in modulating HMGA protein levels.
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Affiliation(s)
- Daniela D'Angelo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto per l'Endocrinologia e l'Oncologia Sperimentale del CNR, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Francesco Esposito
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto per l'Endocrinologia e l'Oncologia Sperimentale del CNR, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Alfredo Fusco
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto per l'Endocrinologia e l'Oncologia Sperimentale del CNR, Università degli Studi di Napoli "Federico II" , Naples , Italy ; Instituto Nacional de Câncer - INCA , Rio de Janeiro, Rio de Janeiro , Brazil
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360
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361
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Abstract
The pathogenesis of Cushing's disease is poorly understood; two recent reports identifying somatic mutations in USP8 in pituitary corticotroph tumors provide exciting advances in this field. These mutations alter EGFR trafficking and signaling, raising the prospect that EGFR inhibitors may move the treatment of this disease into the era of precision medicine.
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Affiliation(s)
- Ursula B Kaiser
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital and Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
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362
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Fukuoka H. New potential targets for treatment of Cushing's disease: epithelial growth factor receptor and cyclin-dependent kinases. Pituitary 2015; 18:274-8. [PMID: 25612787 DOI: 10.1007/s11102-015-0637-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Cushing's disease (CD) is caused by adrenocorticotropic hormone (ACTH)-producing pituitary adenomas (ACTHomas). Drug treatment for CD consists of three strategies: pituitary tumor-targeted therapy, steroidogenesis inhibitors, and glucocorticoid receptor antagonists. All of these strategies are under development, and several new drugs have recently been approved for clinical use or are being tested in clinical trials. Pituitary-targeted drugs are a particularly important method in the treatment of CD. Available pituitary tumor-targeted drugs include a dopamine receptor agonist and a somatostatin analog. Since disrupted cell cycle signaling is clearly associated with pathogenesis of ACTHomas which express active forms of epithelial growth factor receptor (EGFR), cyclins, and the catalytic subunit of cyclin-dependent kinases (CDKs), we focused on these molecules as therapeutic targets for ACTHomas. METHODS In this review, a literature search were performed using PubMed with following terms; Cushing's disease, EGFR, CDKs, cell cycle, and targeted therapy. CONCLUSION Accumulating evidence demonstrates that EGFR and cyclin E-CDK2 may be promising targets for treating ACTHomas.
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Affiliation(s)
- Hidenori Fukuoka
- Division of Diabetes and Endocrinology, Kobe University Hospital, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan,
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363
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Recurrent gain-of-function USP8 mutations in Cushing's disease. Cell Res 2015; 25:306-17. [PMID: 25675982 PMCID: PMC4349249 DOI: 10.1038/cr.2015.20] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 01/30/2015] [Accepted: 02/02/2015] [Indexed: 12/12/2022] Open
Abstract
Cushing's disease, also known as adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (PAs) that cause excess cortisol production, accounts for up to 85% of corticotrophin-dependent Cushing's syndrome cases. However, the genetic alterations in this disease are unclear. Here, we performed whole-exome sequencing of DNA derived from 12 ACTH-secreting PAs and matched blood samples, which revealed three types of somatic mutations in a candidate gene, USP8 (encoding ubiquitin-specific protease 8), exclusively in exon 14 in 8 of 12 ACTH-secreting PAs. We further evaluated somatic USP8 mutations in additional 258 PAs by Sanger sequencing. Targeted sequencing further identified a total of 17 types of USP8 variants in 67 of 108 ACTH-secreting PAs (62.04%). However, none of these mutations was detected in other types of PAs (n = 150). These mutations aggregate within the 14-3-3 binding motif of USP8 and disrupt the interaction between USP8 and 14-3-3 protein, resulting in an elevated capacity to protect EGFR from lysosomal degradation. Accordingly, PAs with mutated USP8 display a higher incidence of EGFR expression, elevated EGFR protein abundance and mRNA expression levels of POMC, which encodes the precursor of ACTH. PAs with mutated USP8 are significantly smaller in size and have higher ACTH production than wild-type PAs. In surgically resected primary USP8-mutated tumor cells, USP8 knockdown or blocking EGFR effectively attenuates ACTH secretion. Taken together, somatic gain-of-function USP8 mutations are common and contribute to ACTH overproduction in Cushing's disease. Inhibition of USP8 or EGFR is promising for treating USP8-mutated corticotrophin adenoma. Our study highlights the potentially functional mutated gene in Cushing's disease and provides insights into the therapeutics of this disease.
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